Generally, an image forming apparatus includes a casing including an opening portion formed at a side surface thereof (e.g., in a width direction), and a sheet supply tray configured to be attached to or installed in an interior of the casing via the opening portion. The sheet supply tray is configured to accommodate a stack of a plurality of sheets and to move between an installed position in which the sheet supply tray is installed in the casing and a pulled position in which the sheet supply tray is pulled out from the installed position.
When the image forming apparatus performs an image forming operation, sheets in the sheet supply tray are fed one by one by a pickup roller to a sheet feeding path inside the casing. Each of the sheets is fed by feeding rollers to an image forming unit for image formation. After the image forming unit forms images onto the sheets, the sheets are discharged onto a discharge tray.
To load a stack of sheets into the sheet supply tray or to change a sheet size, a user manually removes and installs the sheet supply tray relative to the casing.
When the sheet supply tray is manually moved in an inserting direction in which the sheet supply tray is inserted into the casing to install the sheet supply tray therein, the sheet supply tray may be insufficiently inserted, and therefore does not reach an installed position in the casing.
In such a case, improper image formation onto a sheet or sheet feeding problems may occur.